Zhang Yubohan, Li Xin, Wang Xu, Lei Xiao, Gao Jie, Zhang Xu, Ma Yanning, Jin Zuolin
Department of Orthodontics, State Key Laboratory of Military Stomatology and National Clinical Research Center for Oral Diseases and Shaanxi Clinical Research Center for Oral Diseases, School of Stomatology, The Fourth Military Medical University, Xi'an, China.
Department of Stomatology, 900TH Hospital of Joint Logistics Support Force, PLA, Fuzhou, Fujian, China.
J Periodontol. 2025 Jul 8. doi: 10.1002/jper.11373.
To investigate the epidemiology and risk factors of open gingival embrasures (OGE) in adult patients after clear aligner therapy (CAT).
A total of 518 adult patients were recruited to evaluate the prevalence and severity of OGE between central incisors through intraoral photographs; 281 patients with complete lateral cephalometric radiographs and cone-beam computed tomography (CBCT) were selected above to investigate mainly mesiodistal anatomical indicators regarding the occurrence and severity of OGE; and 186 non-extraction (NE) patients were selected from 281 patients to further investigate the relationship between tooth movement or labial-palatal/lingual anatomical indicators with OGE.
The prevalence of OGE was relatively high and significantly associated with tooth extraction. The prevalence and severity of OGE decreased as follows: one-lower-incisor-extraction > two-premolar-extraction > NE types. The interproximal contact point-alveolar crest (ICP-AC) > 5 mm, ΔICP-AC > 0.5 mm, cemento-enamel junction-alveolar crest (CEJ-AC) > 2 mm, and ΔCEJ-AC > 0.2 mm were significantly associated with the occurrence of OGE. ΔCEJ-AC may more sensitively reflect bone loss, meanwhile, CEJ-AC in distal sites was significantly associated with moderate or severe OGE in mesial sites. Intrusion movement < 2 mm and labial inclination < 5° were the warning limits for incisor movement. Furthermore, we found that bone dehiscence and root resorption were significantly associated with OGE.
OGE of varying severity could be accompanied by different degrees of three-dimensional alveolar bone resorption. Moderate-to-severe OGE may occur alongside other complications in orthodontic treatment. This research also provided valuable clinical insights and treatment guidance in CAT.
Clear aligner therapy (CAT) is a favored orthodontic choice for adults, yet it can carry hidden risks to periodontal health. Open gingival embrasure (OGE), or "black triangles" between teeth, can affect aesthetics, promote food impaction, and potentially relate to underlying bone loss. Our large-sample study investigated the incidence of OGE, identified the treatment alternatives associated with increased risk, how OGE related to alterations in tissue loss and tooth movement, and what risks OGE may indicate. The prevalence of OGE is relatively high in adult patients after CAT. Patients with a single lower incisor removed had the highest rates and severity of OGE, followed by those with two premolars extracted, and finally those with no extractions. Detailed imaging revealed that the occurrence and severity of OGE are significantly associated with bone loss, not only between teeth but also from the front-back directions. Additionally, specific thresholds for tooth movement that may elevate OGE risk include excessive incisor intrusion or forward tilting. Importantly, OGE often occurred along with other complications like bone dehiscence or root resorption. Our findings provide anatomical data on the potential three-dimensional tissue loss associated with different severities of OGE and further provide clinical guidance in CAT.
探讨成人患者在使用透明矫治器治疗（CAT）后出现开放性牙龈间隙（OGE）的流行病学特征及危险因素。
共招募518例成年患者，通过口腔内照片评估中切牙间OGE的患病率及严重程度；从上述患者中选取281例有完整头颅侧位片和锥形束计算机断层扫描（CBCT）的患者，主要研究与OGE发生及严重程度相关的近远中解剖学指标；从281例患者中选取186例非拔牙（NE）患者，进一步研究牙齿移动或唇腭/舌侧解剖学指标与OGE的关系。
OGE的患病率相对较高，且与拔牙显著相关。OGE的患病率及严重程度按以下顺序降低：单颗下切牙拔除型＞两颗前磨牙拔除型＞NE型。邻面接触点至牙槽嵴（ICP-AC）＞5 mm、ΔICP-AC＞0.5 mm、牙骨质-釉质界至牙槽嵴（CEJ-AC）＞2 mm及ΔCEJ-AC＞0.2 mm与OGE的发生显著相关。ΔCEJ-AC可能更敏感地反映骨质流失，同时，远中部位的CEJ-AC与近中部位的中度或重度OGE显著相关。切牙压低移动＜2 mm和唇倾度＜5°是切牙移动的预警界限。此外，我们发现骨开窗和牙根吸收与OGE显著相关。
不同严重程度的OGE可能伴有不同程度的三维牙槽骨吸收。中重度OGE可能与正畸治疗中的其他并发症同时出现。本研究还为CAT提供了有价值的临床见解和治疗指导。
透明矫治器治疗（CAT）是成人正畸治疗的首选方法，但它可能对牙周健康存在潜在风险。开放性牙龈间隙（OGE），即牙齿间的“黑三角”，会影响美观，促进食物嵌塞，并可能与潜在的骨质流失有关。我们的大样本研究调查了OGE的发生率，确定了与风险增加相关的治疗方式，OGE与组织流失和牙齿移动变化的关系，以及OGE可能预示的风险。成年患者在CAT后OGE的患病率相对较高。单颗下切牙拔除的患者OGE的发生率和严重程度最高，其次是两颗前磨牙拔除的患者，最后是非拔牙患者。详细的影像学检查显示，OGE的发生和严重程度不仅与牙齿间的骨质流失显著相关，还与前后方向的骨质流失显著相关。此外，可能增加OGE风险的牙齿移动的特定阈值包括切牙过度压低或向前倾斜。重要的是，OGE常与骨开窗或牙根吸收等其他并发症同时出现。我们的研究结果提供了与不同严重程度的OGE相关的潜在三维组织流失的解剖学数据，并进一步为CAT提供了临床指导。
